View report page

15
there was in Southwark in distinguishing between a " secondary " case infected by a previous
sufferer in a household, and a case which, though developing shortly after the occurrence of a
first case in a house, might also itself be regarded as a primary case. This difficulty will be
further discussed later. Of the cases occurring at the time of special prevalence which have been
allocated to column 1, three (Nos. 18, 39 and 47) were notified as enteric fever, but after removal
to hospital it was found that the patients were not suffering from that disease. In the fourth case
(No. 46), the patient was at the seaside at a time which would correspond with the date of infection,
and he had eaten some oysters, to which he attributed his attack, while away from Lambeth at that
time.
As regards the cases in column 3, there was a clear history of consumption of fried fish
from a particular shop (referred to as Mr. T's in the appended notes), at a time which would correspond
with the date of infection, in all the notified cases with the exception of four (Nos. 17, 19,
28 and 36), and there was, a similar history in two other cases indicated by a dagger, thus (†),
which, although not notified, were probably cases of enteric fever.
As regards the four exceptions particulars will be found in the notes; No. 17 was a fatal
case, and, while it is certain that the man frequently purchased fried fish, it could not be ascertained
where he obtained it; Nos. 19 and 28 almost certainly purchased fried fish at Y's shop at
about the time when their illness must have been contracted, but the evidence was less conclusive
with regard to them than with regard to the other cases in column 3; case 36 was that of a child
(related to cases 6 and 16, who were frequent purchasers of Y's'fried fish) who was staying, at
the time when she must have been infected, with an aunt who lived close to Y's shop.
So far, the Lambeth outbreak presents much similarity to that in Southwark, though in
the former, owing to the smaller number of attacks, the figures form a less reliable basis upon
which to found conclusions. Two special difficulties, however, must now be mentioned as deserving
of consideration in connection with the Lambeth outbreak.
In the first place there is the difficulty of distinguishing between primary and secondary
cases in dealing with certain members of households which had been already attacked. Thus—
Cases 3, 21 and 25 were members of the same family.
Case 8 was the sister of case 4.
Cases 6, 16 and 36 belonged to one family.
Cases 7 and 15 were brothers.
Cases 12, 20, 43, 44 and 52 belonged to one family.
Cases 29, 30, 33, 35 , 49 and 54 belonged to one family.
Cases 34 and 37 were sisters.
Cases 41 and 51 were sisters; and case 42 was the child of a lodger living in the
same house.
Some of these cases were no doubt " secondary cases," but it is probable that several of
them (in addition to the first case occurring in each house) were really primary cases, in which the
date of onset of symptoms was later than it was in the 'case which first declared itself in the
household.
Thus—Case 8 sickened only 4 days after case 4.
16 „ 4 „ „ 6.
15 „ 3 „ „ 7.
20 7 12.
33 „ 2 " „ cases 29 and 30.
1 35 ,, 3 „ ,, ,, „
37 „ 2 „ case 34.
42 „ 1 day „ 41.
There can be little doubt that in the above instances the second case (in the case of Nos. 33
and 35 the third and fourth cases) must really be regarded as a primary case, and not as a
"secondary " one.
As regards cases 21 and 25, which occurred in the house in which case 3 occurred, the
interval of time was longer, and the possibility of the later cases being infected by case 3 cannot
be ignored. It is interesting, however, to note, as regards case 3, that the patient was in the
habit of buying fried fish from Y's on his own account, and independently of the rest of the
family, and it is of course conceivable that he and they were infected on distinct and separate
occasions.
The course of the outbreak in Lambeth is not, as in Southwark, such as to suggest
limitation of infective agency to only one or two days. The agency, whatever it was, took
effect in Lambeth about one week earlier than in Southwark. The falling off in the number of
cases after September 4th, and the recrudescence on the 7th and succeeding days corresponding
with the time of maximum prevalence in Southwark, rather lead to the suspicion that infective
property may have been manifested in Lambeth on two separate occasions, one about a week earlier
than the other, and the later one corresponding in date with the time of distribution of infective
material in Southwark. If this supposition be correct it is easy to understand why the difficulty
as regards distinguishing between secondary and primary cases should be more marked in.
Lambeth than in Southwark.
The second difficulty arises from the fact that whereas in Southwark the cases showed a
striking tendency to group themselves around the fried fish shop as a centre, and further to show
diminishing intensity of incidence upon area as the distance from the fried fish shop was increased,
in Lambeth the outbreak was especially manifested in three or four streets in the western half
of the area, while the streets in the eastern half of the area almost entirely escaped. This difficulty
was at once pointed out by Dr. Priestley when I first told him of the direction in which the